Geothermal heat recovery operations (also termed as a geothermal heat pump or ground source heat pump) are known in the art and which can provide for either of heating or cooling by pumping heat to or from a subterranean zone beneath a ground surface and by which the relevant assembly employed uses the earth as a heat source (in the winter) or a heat sink (in the summer). In application, geothermal systems are designed to take advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems. Ground source heat pumps are also known as “geothermal heat pumps” although, strictly, the heat does not come from the centre of the Earth, but from the Sun. They are also known by other names, including geoexchange, earth-coupled, earth energy systems.
Depending on latitude, the temperature beneath the upper 6 meters (20 ft) of Earth's surface maintains a nearly constant temperature between 10 and 16° C. (50 and 60° F.), if the temperature is undisturbed by the presence of a heat pump. Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from the ground. Heat pumps can transfer heat from a cool space to a warm space, against the natural direction of flow, or they can enhance the natural flow of heat from a warm area to a cool one.
The core of the heat pump is a loop of refrigerant pumped through a vaporcompression refrigeration cycle that moves heat. Seasonal variations drop off with depth and disappear below 7 meters (23 ft) due to thermal inertia. Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer. A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling). Some systems are designed to operate in one mode only, heating or cooling, depending on climate.